Electrical utilities and principal power consuming industries employ a wide variety of instruments in evaluating, costing and analyzing distributed electrical energy and consumed power. Rather extensive collections of instruments will be found both adjacent power consumption and generation sites as well as at terminal or tie points of distribution grids. Generally each principal distribution path of a utility system will be monitored for a significant number of both real and reactive energy and power parameters, such parameters being acquired for visual readout by operational personnel, by remote reading by a data acquisition system, as well as for storage upon magnetic media or the like. Depending upon the particular metering and analytic approach taken by a user, recorded data then are manipulated to achieve a desired evaluation of the consumption and distribution process. Of the parameters the industry will select, for example, watthour, varhour, Qhour, Volt.sup.2 hour, volthour, ampere.sup.2 hour and amperehour will be employed. Additionally, watt, var, Q, ampere and volt analog functions may be utilized in various combinations.
As is apparent from the above, the instrumentation which will be required for any given path monitoring function may be extensive. In this regard, the general practice of industry has been to provide a collection of instruments and group them, for example in a dedicated panel structure for operator utilization. For the most part, each instrument within an assemblage thereof is dedicated to a singular function, i.e. separate meters are utilized for the generation of watthours and volthours. Similarly, separate transducers, each employing polyphase current and voltage transformers in combination with dedicated multiplication circuits are utilized for the generation of such analog functions as watt, var and Q. Generally, for power related monitoring applications, six transformers will be incorporated within each such instrument in combination with six dedicated multiplier circuits. Further, the instruments themselves are assembled as an integral unit, any maintenance being carried out by resort to rather involved disassembly procedures. Such maintenance further requires a dismantling of the instruments to carry on necessary calibration procedures utilizing standards and like devices. The availability of user access at the face of these instruments for calibration and repair could be of considerable practical benefit. To the present, however, only metering function providing for meter readout and pulse initiator derived power consumption output signals have been incorporated in housing structures which are accessable from the front panel region.
Accordingly, the myriad of instruments assembled within a typical installation generally must be calibrated and maintained by labor intensive procedures of removal of entire instruments from mounting panels and the like. Further, the necessary collection of instrumentation for each distribution path necessarily evokes somewhat extensive and concomitantly costly installations in terms of space for carrying out necessary monitoring and data acquisition procedures.